1. Field of the Invention
The present invention relates generally to network communication, and more particularly, to a method for transmitting and receiving packets through an optimized route between nodes through the application of Mobile Adhoc for Network Mobility (MANEMO) in a sensor network consisting of Internet Protocol (IP) version 6 over Low power Wireless Personal Area Network (6LoWPAN) based sensor nodes.
2. Description of the Related Art
The interworking of IP networks is indispensable in the efficient management of a sensor network. IP version 6LoWPAN has been proposed by the Internet Engineering Task Force (IETF) Working Group for use in Transmission Control Protocol/Internet Protocol (TCP/IP) on IEEE 802.15.4. The 6LoWPAN utilizes IP version 6 (IPv6) in a low-power Wireless Personal Area Network (WPAN) that employs IEEE 802.15.4 Physical Layer/Media Access Control Layer (PHY/MAC). Generally, 6LoWPAN includes devices that operate together and are physically connected to application environments in the real world. Wireless sensors, or sensor nodes, are examples of such devices.
Network Mobility (NEMO) supports network-based mobility through the use of Mobile Routers (MRs) during network movement. NEMO provides persistent Internet connections to a variety of mobile nodes and fixed nodes that exist in subnets in the MRs. Each NEMO MR includes at least two network interfaces, which are divided into egress and ingress interfaces. An egress interface supports network mobility by accessing external networks or other NEMOs, while an ingress interface forms a subnet in the MR. NEMO may form an overlapping mobile network by accessing other NEMOs through the egress interfaces of the MRs. However, if a level of overlapping mobile networks increases, route optimization fails in a data delivery process as shown in FIG. 1. Specifically, the excess overlapping causes a pinball routing problem that may increase packet overhead in a packet tunneling process. Mobile Adhoc for NEMO (MANEMO) has been proposed to reduce overhead and transmission delay time that occur in the packet delivery process, by solving the non-optimized route problem in the overlapping NEMO networks.
FIG. 2 is a diagram illustrating a packet delivery process through MRs in a MANEMO environment.
When MANEMO performs communication between MRs belonging to an overlapping NEMO networks, it enables direct communication between the MRs through the use of an Ad-hoc routing protocol, Mobile Adhoc Network (MANET). Therefore, the bidirectional tunnel to Home Agents (HAs), which was created for communication in the NEMO environment, is not required, reducing the packet overhead that was increased due to the tunneling. In addition, the MRs in the overlapping networks directly communicate with one another using a MANET routing protocol without passing through the HAs in the IPv6 network, reducing the packet transmission delay time.
There have been many attempts to apply the MANEMO environments to the 6LoWPAN network. When 6LoWPAN MRs supporting 6LoWPAN-based network mobility has formed an overlapping network, route optimization for packet delivery may not be accomplished during communication between a Mobile Network Node (MNN) located inside the 6LoWPAN and a Correspondent Node (CN) located outside the 6LoWPAN, or communication between 6LoWPAN MNNs in different 6LoWPAN mobile networks.
When an overlapping level of a 6LoWPAN network increases and a NEMO Basic Support protocol is applied, the route for packet delivery becomes more complicated increasing the packet overhead. This occurs because all packets between an MNN and a CN are transmitted and received through a bidirectional tunnel between MRs and HAs, which prohibits the formation of an optimized route between the two nodes. Hence, even though the CN is located nearby, the packet may be routed through a long route inefficiently, increasing the transmission delay time. If the conventional MANEMO environment is applied to solve these problems, an optimized route can be determined by applying the Ad-hoc routing protocol between 6LoWPAN MRs. However, a method is not available for applying the MANEMO technology in accordance with the 6LoWPAN environment.